The present invention relates to window blinds and, more particularly to a cord winding mechanism for a cordless window blind.
A cordless window blind is operable to raise and lower slats through elastic devices, without manually operating blind cords. Common cordless window blinds include shutters, honeycomb blinds, and Roman blinds. The cordless window blinds hide blind cords inside the blinds, and install winders on tops of the blinds to collect the blind cords, thus winding or unwinding the blind cords to raise or lower the blinds.
FIG. 6 shows a conventional H-shaped winder 80. A blind cord 5 is wound round the winder 80 in a slot 82 of the winder 80. The H-shaped winder 80 generally operates in one of two operation modes, one of which is randomly winding blind cords and the other of which is adding a complicated cord guiding mechanism. When randomly winding blind cords, the blind cord 5 is wound without guide, thereby, the blind cord 5 is easily disorderly wound round the winder 80. A window blind using two winders 80 and operating in the mode of randomly winding cords easily leans to one side when the two winders 80 rotate the same number of turns while the lengths of the wound blind cords of the two winders 80 are different. When adding a complicated cord guiding mechanism, and when the winder 80 rotates a turn, the cord guiding mechanism moves a distance of a diameter of the blind cord 5. Therefore, the lengths of the wound blind cords of two winders 80 operating in the mode of adding a complicated cord guiding mechanism are the same, and a window blind using the two winders 80 operating in the mode of adding a complicated cord guiding mechanism will not lean to one side. However, the cord guiding mechanism is complicated and costly, and is easily damaged.
FIG. 7 shows another conventional winder 90. The winder 90 defines a helical slot 92 in a circumference of the winder 90. A blind cord 5 is orderly wound in the helical slot 92. However, the winder 90 generally has a large volume, and thus, the winder 90 cannot be used on mini-blinds.